This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application entitled PROJECTION MONITOR HAVING A DARKROOM filed with the Korean Industrial Property Office on Feb. 3, 2000 and there duly assigned Ser. No. 2000/5414.
1. Field of the Invention
The present invention relates to a projection monitor, and in particular to a projection monitor having a darkroom capable of preventing a foreign material such as dust from being penetrated into the interior of a projection monitor and easily assembling the reflection mirrors to a darkroom casing by changing an optical axis of an image projected from an engine.
2. Description of the Background Art
Generally, a video display apparatus capable of projecting an optical energy on a screen is classified into a direct viewing type video display apparatus and a projection type video display apparatus based on a method for displaying an optical energy on a screen.
A CRT(Cathode Ray Tube) which is called as Brown tube is known as a representative one of the straight type video display apparatus. The CRT apparatus has a good resolution. However, the size of the same is increased, the weight and volume of the CRT apparatus is increased for thereby increasing-a fabrication cost.
A LCD(Liquid Crystal Display), a DMA(Deformable Mirror Array), and an AMA(Actuator Mirror Array) are known as the projection type video display apparatus. A projection television or projection monitor is a kind of the projection type video display apparatus. Namely, the projection type video display apparatus generates R, G, B(Red, Green, Blue) colors which are three primary colors of light and obtains a desired image by projecting on a screen using an expanding lens and reflection mirror.
The video projection of Japan Utility model laid-open No. 4-096182 uses a CRT as a video image generation apparatus and is directed to projecting the image projected by the CRT on a screen and expanding the image. Therefore, the above video projector may be considered as a projection type video display apparatus. In the case of the above video projector, a shield casing is installed between the CRT of the cabinet and the screen for sealing a projection way of the video image, so that a certain problem is caused due to dust, and a resolution is decreased due to a light scattering problem.
However, the above-described video projector uses a large size CRT as a video projecting apparatus capable of projecting an image on the screen and one reflection mirror. Therefore, there is a limit for increasing the distance between the CRT and the screen, which is related to the screen expanding ratio. The above-described projector has a resolution which is worse compared to the projection type video display apparatus which uses the engine as a video display apparatus. When expanding the size of the screen, the resolution is decreased. The entire weight and volume of the system are increased, and the fabrication cost is increased.
Accordingly, it is an object of the present invention to provide an improved projection monitor.
It is also an object of the present invention to provide a projection monitor with a darkroom casing is capable of preventing a penetration of a foreign material such as dust which may scatter light of the engine projected on a screen and preventing any leakage of the light from the engine and obtaining an excellent resolution.
It is yet another object of the present invention to provide a projection monitor with a larger screen expanding ratio which is achieved by having three reflection mirrors between the engine and the screen and by having sufficient distance between the engine and the screen.
It is still yet another object of the present invention to provide for easy installation of the reflecting mirrors within the darkroom casing.
To achieve the above objects, there is provided a projection monitor having a darkroom casing which includes a front casing having a screen installed on a front surface of the same, a rear casing engaged to the back of the front casing and forming a sealed space behind the front casing, a darkroom casing engaged to the back of the front casing in the rear casing and forming a darkroom by which a foreign material and light do not penetrate into the interior of the rear casing, an engine installed in the interior of the darkroom casing and generating and light in accordance with an input of an electrical video signal and projecting an image, and at least three reflection mirrors attached on an inner wall of the darkroom casing and sequentially reflecting the image projected by the engine and guiding the image to the screen and being inserted into fixing ribs installed parallel on the ceiling of the darkroom casing like a drawer.
A bracket is engaged to a front rim portion of the reflection mirror fixed on the ceiling of the darkroom casing and inserted between the ceiling of the darkroom casing and the fixing rib when the reflection mirror is inserted between the ceiling of the darkroom casing and the fixing rib for thereby preventing light from entering or escaping the darkroom casing. The rear wall of the darkroom casing is slanted in the back direction, and at least one among the reflection mirrors is fixed by the frame at both sides of the same and is attached on the rear wall of the darkroom casing.